The use of porous or open-weave cloths, textiles or fabrics to shield plants or animals from adverse environmental conditions has been known for some time. Adequate shielding can actually be provided in many cases by an only partial blocking of the effect--which may for example be wind, sun, or rain--by an open-weave fabric usually made by knitting or weaving (for example) of smut fibres of a plastics material such as a nylon or polypropylene. The plastics material is treated with additives to reduce environmental degradation. Usually the fabric is made and used in the form of a long strip, typically one, two, or preferably three meters wide and perhaps 500 meters long, although this can be cut to any length. The plastics fibres of these fabrics (typically polyethylene, polypropylene or polyester yams) are inherently flexible, stretchy, and liable to abrade. They have some tensile strength but it is not sufficient to support long spans of their own weight over a span, and over a long period, even in the absence of any extra stresses due to wind loading or the weight of trapped snow or hail. For this reason it is customary to sling cables capable of carrying tensile force over gaps above the area to be protected and attach the edges of the shielding fabrics to those cables. These cables may be made of high-tensile steel, for example, and they may be surface-treated against corrosion.
The preferred plastic fabrics also have minimal shear strength in the plane of the fabric which results in minimal transfer of load between the tensed steel cables running parallel to the fabric selvedges, particularly between attachment points and adjacent yarns not directly attached. Therefore it is important to be able to hold the strips of fabrics in a way that transfers the load to the maximum number of yarns from each attachment point in order to successfully build a durable, reliable and economical structure using these fabrics. At the same time, the system must be easy to install in the field.